Read the output of the script and follow the instructions it gives - it'll ask you to put a line into your .bashrc or similar file. Then log out of your terminal and open a new one, and run:
rvm install 1.8.7
rvm use 1.8.7

and then run
sudo gem update --system
and
sudo gem install bundler

You may need to run each of these and then run them again for it to work.

Note: 'ruby QuoraCrawler.rb -h' and 'ruby QuoraStats.rb -h' will give you all the flags if you just want to process specifics.

Right now QuoraStats.rb is only outputting limited detail, but if you call the load_all_data method on a QuoraUser object in irb, you can play around with extracting out all the data that interests you.